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tpm: reduce tpm polling delay in tpm_tis_core

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The existing wait_for_tpm_stat() polls for the chip status after
5msec sleep. As per TCG ddwg input, it is expected that tpm might
return status in few usec. So, reducing the delay in polling to
1msec.
Similarly, get_burstcount() function sleeps for 5msec before
retrying for next query to burstcount in a loop. If it takes
lesser time for TPM to return, this 5msec delay is longer than
necessary.

After this change, performance on a TPM 1.2 with an 8 byte
burstcount for 1000 extends improved from ~14sec to ~9sec.

Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
This commit is contained in:
Nayna Jain 2017-10-17 16:32:31 -04:00 committed by Jarkko Sakkinen
parent 87cdfdd19a
commit cf151a9a44
1 changed files with 8 additions and 2 deletions
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10
drivers/char/tpm/tpm_tis_core.c
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@ -31,6 +31,12 @@
#include "tpm.h" #include "tpm.h"
#include "tpm_tis_core.h" #include "tpm_tis_core.h"
/* This is a polling delay to check for status and burstcount.
* As per ddwg input, expectation is that status check and burstcount
* check should return within few usecs.
*/
#define TPM_POLL_SLEEP 1 /* msec */
static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask, static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
bool check_cancel, bool *canceled) bool check_cancel, bool *canceled)
{ {
@ -82,7 +88,7 @@ again:
} }
} else { } else {
do { do {
tpm_msleep(TPM_TIMEOUT); tpm_msleep(TPM_POLL_SLEEP);
status = chip->ops->status(chip); status = chip->ops->status(chip);
if ((status & mask) == mask) if ((status & mask) == mask)
return 0; return 0;
@ -224,7 +230,7 @@ static int get_burstcount(struct tpm_chip *chip)
burstcnt = (value >> 8) & 0xFFFF; burstcnt = (value >> 8) & 0xFFFF;
if (burstcnt) if (burstcnt)
return burstcnt; return burstcnt;
tpm_msleep(TPM_TIMEOUT); tpm_msleep(TPM_POLL_SLEEP);
} while (time_before(jiffies, stop)); } while (time_before(jiffies, stop));
return -EBUSY; return -EBUSY;
} }